It is well-known to provide covers for drinking containers to prevent the spillage of the contents of the container. Many prior art covers incorporate an opening in the top of the cover in order to allow drinking of the contents either in the normal drinking fashion or by the insertion of a straw. Some covers have an opening which is sealed by a depressible tab such that when the tab is depressed by the insertion of a straw, the opening is unsealed for drinking the contents of the container. U.S. Pat. No. 3,048,317 issued to Cochrane et al. discloses one such lid having an opening for a straw disposed in a depression formed in the lid with an integrally formed hinged flap in the bottom of the depression. The hinged flap is severed from the lid about the majority of the periphery of the flap to pivot open when a pressure is exerted on the flap by the end of a straw. However, unless the hinged opening is exactly the same diameter as the straw, the fluid within the cup may spill out the opening between the straw and the sides of the opening once the hinged flap has been pivoted open.
Other covers utilize a releasable drinking flap in order to prevent the sloshing of the contents out of the containers. An example of this type of cover is disclosed in U.S. Pat. No. 4,738,373 issued to DeParales, which shows a cover having a hinged tab which is defined by score lines formed in the cover leading from the rim of the cover to a hinge positioned in the medial portion of the cover. A recess is formed in the cover on the opposite of the hinge from the tab, wherein the recess receives the rim portion of the tab once the tab is torn open and pivoted about the hinge in order to retain the hinged tab in an open position. However, if the user desired to use a straw with a cover of this type, the straw would have to be inserted into the opening created by the tearing open of the hinged tab. This would create an exceptionally large opening for a straw, allowing the straw to float about and allowing the contents of the cup to be spilled.
In an effort to overcome the aforementioned shortcomings, other covers have been proposed utilizing both a straw slot and a releasable flap, depending upon the desired use by the consumer. An example of this type of cover is disclosed in U.S. Pat. No. 4,090,660 to Schram et al., which discloses a cup lid having a liftable tab which snap fits on the rim of a cup with a straw slot formed in the portion of the lid constituting the liftable tab. This design, however, does not include a feature incorporated into the lid which will retain the liftable tab in an open position for convenient repeated drinking from the opening created by the liftable tab.
Another example of a prior art drinking lid utilizing both a straw slot and a releasable flap is disclosed in U.S. Pat. No. 5,335,812 issued to Boller, which shows a lid having a straw puncturable area formed in a rupturable depression in the lid. The lid further includes a flap defined by lines of weakness that may be torn and pivoted to overlie a central portion of the lid to retain the flap in an open position. Of course, designs of this general type forming a retaining portion in the center of the lid to hold the flap open as well as forming a separate rupturable depression for a straw are difficult to mold due to the number of depressions and features which must be formed in the cup lid.
Yet another type of prior art drinking lid utilizing both a straw slot and a releasable flap is disclosed in U.S. Pat. No. 3,994,411 issued to Elfelt et al., which shows a lid having a foldback drink opening. A pull tab formed on the edge of the rim of the foldback portion is insertable in a straw slit formed in the lid in order to hold the foldback portion in an open position. This foldback drink opening requires a great amount of attention by the user to insert the pull tab into the narrow straw slot in order to hold the foldback portion of the lid open. Furthermore, since the straw slot must be forced open to receive the pull tab, the straw slot will be slightly ajar when retaining the pull tab which can allow the contents of the cup to spill therethrough.
Clearly, there is a need for a drink-thru cup lid which provides both a straw slot and a tear-back flap which is simple to form and which does not require multiple separate components to be formed in the lid for each drink-thru feature. Moreover, there is a need for a drink-thru cup lid which securably retains the tear-back flap in place within the straw slot depression without rupturing the cup lid in the straw slot area.